Valeo StARS + X System in Microbus Trial
California, Connecticut Governors Slam Federal Government on Climate Change

DaimlerChrysler Developing Series Hybrid Citaro Bus

DaimlerChrysler is developing a series-hybrid version of its Citaro bus, which the company has also used as a platform for its fuel cell bus work. DaimlerChrysler will introduce the system, which will be installed in a Citaro G articulated bus, in the second half of this year. Pilot operation begins early in 2008, and series production is scheduled for 2009.

The Citaro series hybrid uses a downsized diesel engine as the genset to provide power for a lithium-ion battery pack located on the roof. The Citaro hybrid will use four electric wheel hub motors on the center and rear axles of the vehicle, with total output of 320 kW.

When drawing into, standing at and accelerating away from bus stops, the hybrid bus can operate in electric-only mode. DaimlerChrysler anticipates that the hybrid will offer 20% to 30% lower fuel consumption than conventional diesel Citaros.

With diesel-electric hybrid vehicles from Orion in North America, Mercedes-Benz in Europe and Mitsubishi Fuso in Asia, DaimlerChrysler does not only have the longest, but also the most extensive experience with alternative drive systems for commercial vehicles. Therefore the new hybrid drive Citaro is an important step towards cost efficient and zero-emission driving.

—Andreas Renschler, the DaimlerChrysler Board of Management Member responsible for the Truck Group and Buses

The hybrid uses a 4.8-liter diesel rather than the 12-liter unit in a conventional articulated model. The torque curve of the hybrid-bus engine is tailored to the frequent steady-state operation of a series hybrid application, resulting in optimal emissions performance and fuel efficiency.

The smaller engine weighs approximately 450 kg, compared to the 1,000 kg of the 12-liter unit. The hybrid-drive Citaro also dispenses with a conventional automatic transmission, resulting in further weight savings and improved efficiency. The downsizing of the drivetrain components means that the weight penalty of the Citaro hybrid bus over a conventional diesel-powered articulated bus is only around one tonne.

DaimlerChrysler is positioning the hybrid-drive Citaro as a logical step on the way to a fuel-cell-powered urban regular-service bus of the future. In principle, the diesel engine genset would simply need to be replaced by fuel cells. This is also the approach GM is highlighting in its E-Flex family with the series hybrid Volt and the fuel-cell Volt.

DaimlerChrysler’s North American bus subsidiary produces the series-hybrid Orion bus. Since 2003, Orion has won contracts to supply numerous US and Canadian cities, from New York to San Francisco, with a total of some 1,500 Orion VII Hybrid low--floor urban regular-service buses, around 1,000 of which are already on the road. On top of this, there are also options on a further 525 vehicles.

BAE Systems, the provider of the hybrid drive in the Orion, recently announced that it will introduce a lithium-ion battery pack with cells from A123Systems for the HybriDrive beginning next year. (Earlier post.)

Likewise active in the field of series hybrid-drive urban buses is DaimlerChrysler’s Japanese commercial vehicle subsidiary Fuso, with the low-floor Aero-Star model.



Please tell me what is so hard about downsizing this rig and putting it in a full size SUV, or even leaving it the same size and selling it as a super performance SUV.

P.S. who is doing this Chrysler or Daimler?

Bud Johns

20 to 30 percent better consumption? Sounds conservative to me, I would expect more like 40 to 50.


Bud: Wouldn't that depend heavily on the duty cycble. If you put it on the highway you'd hardly get any improvement. Maybe they're averaging.


I imagine diesel buses are already quite efficient.
The local pollution should be greatly reduced if it uses electricity for stop/start.
Note the huge engine reduction: 12L > 4.8L - that is quite a drop.
It has to be the way to go - depending on cost.
Interesting they put the battery on the roof - it would be nicer to get it lower down for CG reasons, but I suppose they will not be taking corners too hard - not like a tesla.


Does anyone know if they would put this technology in a light rail vehicle? About the same size as an articulated bus except with steel wheels. No catenaries or third rail seems like a nice/cheap way to go over traditional light rail.


Couldn't they downsize this technology to apply in something like an S10 or Tacoma pickup? I'm thinking if I could just go 60-100 miles on a charge from plugging in overnight and then only fire up the <1 liter diesel genset if I exceeded my range. Sure, running exclusively on the genset won't give great fuel economy but since I drive mostly short trips, I'd probably get 10k miles on a tank of diesel. Also, owning such a vehicle would be handy in case of a power failure or just as a portable generator for throwing wild parties in remote locations. :-)


According to Ulf Bossel, a manufacturing engineer and previous fuel cell advocate, the way to a sustainable energy future is with sources of renewable energy rather than hydrogen. So, one question is whether DaimlerChrysler is considering bio-diesel in the range extender.

Bossel observed that Mercedes-Benz learned from the very expensive, CUTE (Clean Urban Transport for Europe) project, which used 27 Citaro fuel cell buses, the main benefit, when compared with standard diesel transit, came from regenerative braking. So, another question is what is DCX doing to maximize such gains?


Unlike US Busses, most public transport busses nowadays put in service in europe are low-floor and ultra-low-floor versions. This leaves little to no room where the engine used to go, and the only useable space left is on the roof.

Jerome G

great now construct one for bussiness delivery then for personal vehicules .ps. don't forget roof top solar! remember build it and they'll come

The comments to this entry are closed.